Identifying Risk Factors for Plagiocephaly

Background: Plagiocephaly is a condition in infants in which normal external pressure placed upon the skull causes an abnormal head shape. The prevalence of plagiocephaly increased dramatically following 1992, generally attributed to the American Academy of Pediatrics' 1992 recommendation to place infants to sleep in a non-prone position to reduce risk of Sudden Infant Death Syndrome. That not all infants who sleep supine develop plagiocephaly suggests other factors may play a role. We hypothesized that factors related to intrauterine constraint, birth injury and malformations are associated with plagiocephaly.

Methods: We conducted a case-control data-linkage study, identifying cases born in Washington State in 1987-2002 diagnosed with plagiocephaly at Children's Hospital Craniofacial Center in Seattle before 18 months of age, and linked them to their birth certificates. Five controls per case were randomly selected from Washington State birth certificates. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI).

Results: We analyzed data from 2,476 cases and 13,817 controls. Cases were more likely than controls to be male (adjusted OR [aOR] 2.0, 95% CI 1.8, 2.2); a twin or triplet (aOR 3.2, 95% CI 2.7, 3.7); injured at birth (aOR 1.4, 95% CI 1.2, 1.7); and born with a congenital anomaly (aOR 2.0, 95% CI 1.8, 2.3). Mothers of case infants were more likely to be primiparous and ≥35 years of age at the infant's birth than control mothers.

Conclusion: These findings support the hypothesis that plagiocephaly is associated with malformations, birth injuries and markers of intrauterine constraint.